FullCalendar display HTML in event title

I am updating my Fullcalendar install to V4. I am feeding mine via JSON and I have HTML (some FontAwsome Icons) in my event title. Here is my old V3 code to render my elements:

$(function() {
  $('#calendars').fullCalendar({
    events: '/activities/calendar.json',
    contentHeight: 750,
    displayEventTime: false,
    header: {
      left: '',
      center: 'title',
      right: 'today prev,next'
    },
    businessHours: {
      dow: [1, 2, 3, 4, 5]
    },
    handleWindowResize: true,
    eventLimit: 2,
    eventLimitClick: 'popover',
    eventRender: function(event, element) {
      element.find('.fc-title').html(event.title);
    }
  });
});

The eventRender: is what fails. The new docs don't clearly explain how I my convert this to the new version. With this code in place my calendar simply fails to load with json parse error in the console. If I remove it it works but my HTML is rendered as plain text. I am sure I am missing something obvious and easy here. My JS skill set is not that great.

After some stubmling around I found this:

  document.addEventListener('DOMContentLoaded', function() {
    var calendarEl = document.getElementById('timeline');

    var calendar = new FullCalendar.Calendar(calendarEl, {
      events: '/activities/timeline.json',
      plugins: [ 'resourceTimeline', 'interaction' ],
      header: {
        left: 'prev,today,next',
        center: 'title',
        right: 'resourceTimelineWeek,resourceTimelineMonth,resourceTimelineYear, '
      },
      eventRender: function(info) {
        info.el.querySelectorAll('.fc-title')[0].innerHTML = info.el.querySelectorAll('.fc-title')[0].innerText;
      }
    });

    calendar.render();
  });

I am open to alternate cleaner answers.